Rotary drilling shock absorber



June 28, 1966 J. o. HUGHES ROTARY DRILLING SHOCK ABSORBER 2 Sheets-Sheet 1 Filed Jan. 15, 1964 MAW/JV l/ A v 1 ii a dome: fi. flag/7e:

INVENTOR.

ATTORNY June 28, 1966 J. D. HUGHES 3,257,827

ROTARY DRILLING SHOCK ABSORBER Filed Jan. 15, 1964 2 Sheets-Sheet 2 Jia 1/0/7794 2. f/uyfiea INVENTOR.

ATTORNEY United States Patent 3,257,827 ROTARY DRILLING SHOCK ABSORBER James D. Hughes, 4222 Richmond Ave., Houston 27, Tex. Filed Jan. 15, 1964, Ser. No. 337,836 8 Claims. (Cl. 64-27) This invention relates to improvements in rotary drilling shock absorbers.

In the drilling of wells such as oil and gas wells, particularly by the rotary system in which a tubular drill string carrying a bit is rotated while drilling fluid is circulated through the interior of the drill string to the area of the bit and thence upwardly through the annular space between the drill string and the well Wall, the drill string is subjected to numerous types of shocks resulting from the engagement of the bit with the rock surfaces encountered during drilling. These shocks may be in the form of vertical shock waves resulting from bouncing of the bit from rock surfaces of varying hardness which it encounters and in the form of torsional shocks which result when the rotation of the bit is momentarily restrained by friction and then released when suflicient torque is imposed on the drill string. These varying types of shocks are seriously damaging to parts of the drill string and their inhibition or elimination is greatly to be desired.

Various types of shock absorber designs have been developed to overcome the problems mentioned above and the following patents are illustrative of some of the several prior designs:

No. 2,620,165, CrickmerjNo. 2,765,147, Vertson; No. 3,033,011, Garrett; No. 3,099,918, Garrett.

These prior designs all employ a common arrangement in providing inner and outer telescoping drive members connectible between sections of the drill string and providing an annular space therebetween in which are mounted or positioned different types of shock absorbing elements. In the case of the Garrett patents, listed above, a continuous sleeve constructed of resilient material, such as rubber, is molded or vulcanized to both the inner and outer drive members of the device forming a permanent resilient connection therebetween.

In the case of the Crickmer and Vertson devices, separable rings are arranged in the annular space. The rings in each instance include metal housings or frames to which resilient material is permanently vulcanized or molded, the rings being splined or keyed to the inner and outer drive members.

These several prior art devices all are subject to some deficiencies in use. The devices of the Garrett patents, because of the permanent connection of the resilient sleeve to both the drive members, necessitate the replacement of the entire structure in the event of substantial wear or destruction of the connecting sleeve, a condition which will occur frequently under the stresses imposed.

In the case of the Crickmer and Vertson type devices, wear of the resilient elements usually necessitates complete replacement of the entire ring, including both the metal and non-metal portions thereof. Replacement or repair of the prior art devices mentioned is generally a relatively costly and inconvenient matter.

The present invention has for its primary object the provision of an improved form of rotary drill shock absorber which obviates the disadvantages of the prior art devices and provides a relatively simple design employing a novel form of what I term force transfer rings, employing removable or replaceable resilient elements, in the form of blocks or plugs, for transmitting the necessary torque between the drive members and for absorbing the various shocks and vibrations to which the drill string is subjected and which, upon failure of any of the resilient elements, will automatically provide effective 1 is made flush with that of upper and lower subs 16 and v 3,257,827 Patented June 28, 1966 ice metal-to-metal drive connections between the drive members of the shock absorbers.

A further object is the provision of a shock absorber of the general type described in which the force transfer rings are formed with oppositely extending clutch teeth shaped to complement the teeth of the adjacent transfer rings and to provide spaces between-the engaged teeth in which are removably positioned blocks of resilient material. The clutch teeth on the ends of the outermost transfer rings are also made complementary to cooperating clutch teeth provided on the respective drive members.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful embodiment in accordance with this invention.

In the drawing:-

FIG. 1 is an elevational view, partly in section, showing the shock absorber device mounted in a drill string extending into a well bore;

FIG. 2 is an enlarged fragmentary view, partly in section, of the shock absorber device;

FIG. 3 is a cross-sectional view taken generally along line 3-3 of FIG. 2;

FIG. 4 is a perspective view of one of the force transfer rings; and

FIG. 5 is a top plan view of the force transfer ring viewed along line 55 of FIG. 4.

Referring to the drawing, the shock absorber device in accordance with this invention, comprises a generally tubular sleeve member comprising the outer drive member of the device having an axial bore 11 and a tubular mandrel or inner drive member 12 of somewhat smaller diameter than bore 11. Inner member 12 also has an axial bore 13 and is threadedly received at its lower end in a lower sub 14 by which the shock absorber is threadedly connected to a drill bit 15. It will be understood that normally one or more drill collars (not shown) will be positioned in the drill string above bit 15, but these have not been shown as they form no part of the present invention. It will be understood that the shock absorber device may be placed anywhere in the drilling string al.- though normal practice is to place such devices at the bottom of the string above the bit and below whatever number of drill collars is being run. Outer drive member 10 is composed of an upper sub or coupling member 16, an intermediate shell 17, and a lower thrust sub or coupling member 18, which are coaxially inter-connected. Upper sub 16 is provided at its upper end with a threaded pin 16a for connection to a drill pipe P or to a drill collar and is reduced somewhat in external diameter at a point adjacent its lower end to form the external shoulder 19 about the reduced diameter portion 20. The latter is externally threaded at 21 to be threadedly received in the upper end of shell 17, the external diameter of which 18. The lower end of portion 20 terminates in an annular shoulder shaped to define the downwardly projecting circumferentially arranged clutch teeth 22 surrounding bore 11. Lower thrust sub 18 has its upper end portion reduced somewhat in external diameter to define an annular shoulder 18a about a reduced diameterportion 23 which is externally threaded at 24 to be threadedly received in the lower end of shell 17. The inner end of reduced portion 23 forms an upwardly facing annular shoulder 25 surrounding the bore of sub 18. Thrust sub 18 is -connterbored from its lower end to form the stuffing box 26 in which is positioned seal packing 27 adapted to form a fluid-tight slidable seal about mandrel 12. A gland nut 28 is screwed into the lower end of stufling box 26 for compressing packing 27. Packing rings, such as O-rings 2929, are positioned to seal between the ends of shell 17 and the respective threaded portions 20 and 23. The upper end of mandrel 12, which extends into bore 11 within upper sub 16, is provided about its exterior with seal packing to form a slidable fluid-tight seal between 1 mandrel 12 and the wall of bore 11. Intermediate its ends mandrel 12 has an annular enlargement 31 which is receivable inside the bore of shell 17 and defines at its lower end a downwardly facing annular shoulder 32 which is abuttable against shoulder 25 on the lower thrust sub. A thrust ring 33, such as a Teflon ring, may be mounted between shoulders 25 and 32, The upper end of enlargement 31 defines an annular upwardly facing shoulder which is formed to provide upwardly projecting circumferentially arranged clutch teeth 34, which are complementary to clutch 22 on the lower end of the upper sub. The difference between the external diameter of mandrel 12 and the inner diameter of shell 17 forms an annular space 35 terminating at its opposite ends in the shoulders carrying the oppositely facing clutch teeth 22 and 34.

A plurality of force transfer rings 36 having axial bores 37 are stacked in superimposed coaxial relation in annular space 35, mandrel 12 extending through their several bores 37. The opposite ends of each of the rings 36 are provided with oppositely extending clutch teeth 38, each having a substantially vertical forward face 38a and a sloping trailing face 36b defining the spaces 39 between successive teeth and joined by a fiat bottom 380. The teeth and the spaces therebetween are of identical shape to clutch teeth 22 and 34 and their respective spaces 22a and 34a, so that either end of each transfer ring may complement and mesh with clutch teeth 22 and 34 as well as with the clutch teeth of every other transfer ring. Preferably the clutch teeth at one end of each transfer ring will be staggered angularly relative to the clutch teeth on the opposite end of that transfer ring and the teeth on the opposite ends of the rings will face in opposite directions.

When one set of the clutch teeth are in mesh with any other set the vertical faces 38a of each of the engaged teeth will be positioned parallel to each other and angularly spaced apart to form vertical side walls for spaces 39 which will cooperate with the bottom walls 380 of the respective spaces to form a substantially rectangular enclosure. A transfer element,40 constructed of resilient composition material is mounted in each of the spaces 39 and in elevational view will have a generally rectangular configuration corresponding in shape and size to spaces 39 as defined by the opposed tooth faces 38a and bottom walls 380 of each engaged pair of clutch teeth so as to fit snugly therein. In crosssection, transfer elements 40 may be generally prismatic, circular, or arcuate as may be required in accordance with the physical properties of the resilient material best adapted to the environment in which the shock absorber is to function.

Elements 40 are made slightly longer than the vertical height of teeth 38 (or of teeth 22 or 34) so as to project a short distance beyond the ends of the clutch teeth and thereby function to vertically space the transfer rings apart and from the shoulders carrying clutch teeth 22 and 34. The spaces 41 so provided between the clutches may be varied as desired to provide space for compression of the resilient transfer elements when under load and main- 'tain the metal portions of the transfer rings and the end clutches out of engagement.

The opposite ends of each of the transfer elements may be dished or rounded, as shown, to provide additional space for deformation and cold flow of the resilient composition. Obviously a void space could also be provided by a hole running the length of the element to provide alternative additional space.

In assembly of the shock absorber, the number of transfer rings employed may be varied as desired to conform with the load requirements in each installation. When the drill string is rotated, the torque required to rotate the bit will be transferred through the engaged clutch teeth and the intervening transfer elements which, when arranged as described, will efficiently transmit the torque while at the same time will effectively absorb both vertical vibrations and torsional shocks occurring during the drilling operation.

The several seals provided between the inner and outer parts of the tool will prevent entrance of the circulating drilling fluids and well fluids which may be encountered into annular space 35 and thereby prevent erosion or other deleterious effects thereof on the composition transfer elements.

Should any of the transfer elements be worn out or destroyed during use, this will only mean the associated clutch teeth will come into direct contact during engagement and the torsional forces will continue to be transmitted as required. Moreover, when the transfer elements have become sufficiently worn to require replacement, it will be seen that it is only necessary to replace the transfer elements themselves, as the transfer rings and the other parts of the shock absorber will ordinarily not require replacement. The device thus constitutes a very economical construction which has an exceptionally high degree of torque transfer and vibration absorption efficiency.

Transfer elements 40 may be made of natural or synthetic rubber or of the various resilient plasticcompositions which are now available, including materials such as nylon, which may be reinforced with glass fibers or other flexible reinforcing materials.

It will be understood that various changes and modifications may be made in the details of the illustrative embodiments .within the scope of the appended claims but Without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is: 1. A rotary drilling shock absorber, comprising an outer tubular member having an axial bore and connectible at one end to one section of a rotary drilling string, an inner tubular member having an axial bore connectible at one end to another section of said rotary drilling string and coaxially insertable into the bore of said outer member to define an annular space therebetween, annular shoulders on the respective members at opposite ends of said annular space, said shoulders carrying oppositely facing clutch teeth, a plurality of separate force transfer rings stacked in said annular space concentrically between the members, the opposite ends of each of said transfer rings carrying oppositely facing clutch teeth of complementary shape to those carried by said shoulders and by each of the other transfer rings,

said clutch teeth being shaped to define when engaged a.

plurality of circumferentially spaced generally rectangular recesses therebetween and force transfer elements of generally rectangular configuration removably disposed in said recesses, the vertical dimension of said elements being somewhat greater than that of the clutch teeth whereby to maintain adjacent transfer rings in spaced apart relation, said elements being constructed of flexible resilient non-metallic material.

2. A rotary drilling shock absorber, comprising an outer tubular member having an axial bore and connectible at one end to one section of a rotary drilling string, an inner tubular member having an axial bore connectible at one end to another section of said rotary drilling string and coaxially insertable into the bore of said outer member to define an annular space therebetween, annular shoulders on the respective members at opposite ends of said annular space, said shoulders carrying oppositely facing clutch teeth, a plurality of separate force transfer rings stacked in said annular space concentrically between the members, the opposite ends of each of said transfer rings carrying oppositely facing clutch teeth of complementary shape to those carried by said shoulders and by each of the other transfer rings, said clutch teeth being shaped to define when engaged a plurality of circumferentially spaced generally rectangular recesses therebetween, force transfer elements of generally rectangular configuration removably disposed in said recesses, the vertical dimension of said elements being somewhat greater than that of the clutch teeth whereby to maintain adjacent transfer rings in spaced apart relation, said elements being constructed of flexible resilient non-metallic material, and means forming fluid-tight seals between said inner and outer members at the opposite ends of said annular space.

3. A rotary drilling shock absorber, comprising an outer tubular member having an axial bore and connectible at one end to one section of a rotary drilling string, an inner tubular member having an axial bore connectible at one end to another section of said rotary drilling string and coaxially insertable into the bore of said outer member to define an annular space therebetween, annular shoulders on the respective members at opposite ends of said annular space, said shoulders carrying oppositely facing clutch teeth, a plurality of separate force transfer rings stacked in said annular space concentrically between the members, the opposite ends of each of said transfer rings carrying oppositely facing clutch teeth of complementary shape to those carried by said shoulders and by each of the other transfer rings, the clutch teeth on one end of each transfer ring being angularly staggered relative to the clutch teeth on the opposite end of said transfer ring, said clutch teeth being shaped to define when engaged a plurality of circumferentially spaced generally rectangular recesses therebetween, and force transfer elements of generally rectangular configuration removably disposed in said recesses, the vertical dimension of said elements being somewhat greater than that of the clutch teeth whereby to maintain adjacent transfer rings in spaced apart relation, said elements being constructed of flexible resilient non-metallic material.

4. A rotary drilling shock absorber, comprising an outer tubular member having an axial bore and connectible at one end to one section of a rotary drilling string, an inner tubular member having an axial bore connectible at one end to another section of said rotary drilling string and coaxially insertable into the bore of said outer member to define an annular space therebetween, said outer member comprising an upper coupling member having an externally threaded pin member at its lower end, a lower coupling member havingv an externally threaded pin member at its upper end, and a tubular shell having internally threaded portions at its opposite ends to threadedly receive the respective pin members, the inner end of said upper pin member defining a downwardly facing annular shoulder at the upper end of said annular space, an annular enlargement on said inner member receivable within said shell, the upper end of said enlargement defining an upwardly facing annular shoulder at the lower end of said annular space, the lower end of said enlargement defining shoulder means abuttable with the inner end of said lower pin member, said annular shoulders carrying oppositely facing clutch teeth, a plurality of force transfer rings stacked in said annular space concentrically between the members, the opposite ends, of each of said transfer rings carrying oppositely facing clutch teeth of complementary shape to those carried by said annular shoulders and by each of the other transfer rings, said clutch teeth being shaped to define when engaged a plurality of circumferentially spaced generally rectangular recesses therebetween, and force transfer elements of generally' rectangular configuration disposed in said recesses, the vertical dimension of said elements being somewhat greater than that of the clutch teeth whereby to maintain adjacent transfer rings in spaced apart relation, said elements being constructed of flexible resilient non-metallic material.

5. A rotary drilling shock absorber, comprising an outer tubular member having an axial bore and connectible at one end to one section of a rotary drilling string, an inner tubular member having an axial bore connectible at one end to another section of said rotary drilling string and coaxially insertable into the bore of said outer member to define an annular space there-between, said outer member comprising an upper coupling member having an externally threaded pin member at its lower end, a lower coupling member having an externally threaded pin member at its upper end, and a tubular shell having internally threaded portions at its opposite ends to threadedly receive the respective pin members, the inner end of said upper pin member defining a downwardly facing annular shoulder at the upper end of said annular space, an annular enlargement on said inner member receivable within said shell, the upper end of said enlargement defining an upwardly facing annular shoulder at the lower end of said annular space the lower end of said enlargement defining shoulder means abuttable with the inner end of said lower pin member, said annular shoulders carrying oppositely facing clutch teeth, a plurality of force transfer rings stacked in said annular space concentrically between the members, the opposite ends of each of said transfer rings carrying oppositely facing clutch teeth of comple mentary shape to those carried by said annular shoulders and by each of the other transfer rings, said clutch teeth being shaped to define when engaged a plurality of circumferentially spaced generally rectangular recesses there'- between, and force transfer elements of generally rectangular configuration disposed in said recesses, the vertical dimension of said elements being somewhat greater than that of the clutch teeth whereby to maintain adjacent transfer rings in spaced apart relation, said elements being constructed of flexible resilient non-metallic material, means forming a slidable seal between the inner end of the inner member and the bore wall of said upper coupling member, and seal means arranged between said inner member and said lower coupling member below said enlargernent.

6. A rotary drilling shock absorber, comprising an outer tubular member having an axial bore and connectible at one end to one section of a rotary drilling string, an inner tubular member having an axial bore connectible at one end to another section of said rotary drilling string and coaxially insertable into the bore of said outer member to define an annular space therebetween, said outer member comprising an upper coupling member having an externally threaded pin member at its lower end, a lower coupling member having an externally threaded pin member at its upper end, and a tubular shell having internally threaded portions at its opposite ends to threadedly receive the respective pin members, the inner end of said upper pin member defining a downwardly facing annular shoulder at the upper end of said annular space, an annular enlargement on said inner member receivable within said shell, the upper end of said enlargement defining an up wardly facing annular shoulder at the lower end of said annular space, the lower end of said enlargement defining shoulder means abuttable with the inner end of said lower pin member, said annular shoulders carrying oppositely facing clutch teeth, a plurality of force transfer rings stacked in said annular space concentrically between the members, the opposite ends of each of said transfer rings t carrying oppositely facing clutch teeth of complementary shape to those carried by said annular shoulders and by each of the other transfer rings, the clutch teeth on the opposite ends of each of the transfer rings being angularly staggered with respect to each other, said clutch teeth being shaped to define when engaged a plurality of, circumferentially spaced generally rectangular recesses therebetween, and force transfer elements of generally rectangular configuration disposed in said recesses, the vertical dimension of said elements being somewhat greater than that of the clutch teeth whereby to maintain adjacent transfer rings in spaced apart relation, said elements being constructed of flexible resilient non-metallic material.

7. A rotary drilling shock absorber, comprising an outer tubular member having an axial bore and connectible at one end to one section of a rotary drilling string, an inner tubular member having an axial bore connectible at one end to another section of said rotary drilling string and coaxially insertable into the bore of said outer member to define an annular space therebetween, circumferentially spaced, oppositely facing clutch teeth on the respective members at opposite ends of said annular space, a plurality of separate force transfer rings stacked in said annular space concentrically between the members, the opposite ends of each of said transfer rings carrying oppositely facing clutch teeth of complementary shape to those carried by said members and by each of the other transfer rings, said clutch. teeth being shaped to define when engaged a plurality of circumferentially spaced generally rectangular recesses therebetween, and force transfer elements removably disposed in said recesses, the vertical 20 dimension of said elements being somewhat greater than that of the clutch teeth whereby to maintain adjacent transfer rings in spaced apart relation, said elements being constructed of flexible resilient non-metallic material.

8. A rotary drilling shock absorber according to claim 7 including seal means arranged between said inner and outer members to seal off said annular space from the bores of said members.

References Cited by the Examiner UNITED STATES PATENTS MILTON KAUFMAN, Primary Examiner.

BROUGHTON G. DURHAM, Examiner.

D. H. THIEL, Assistant Examiner. 

7. A ROTARY DRILLING SHOCK ABSORBER, COMPRISING AN OUTER TUBULAR MEMBER HAVING AN AXIAL BORE AND CONNECTIBLE AT ONE END TO ONE SECTION OF A ROTARY DRILLING STRING, AN INNER TUBULAR MEMBER HAVING AN AXIAL BORE CONNECTIBLE AT ONE END TO ANOTHER SECTION OF SAID ROTARY DRILLING STRING AND COAXIALLY INSERTABLE INTO THE BORE OF SAID OUTER MEMBER TO DEFINE AN ANNULAR SPACE THEREBETWEEN, CIRCUMFERENTIALLY SPACED, OPPOSITELY FACING CLUTCH TEETH ON THE RESPECTIVE MEMBERS AT OPPOSITE ENDS OF SAID ANNULAR SPACE, A PLURALITY OF SEPARATE FORCE TRANSFER RINGS STACKED IN SAID ANNULAR SPACE CONCENTRICALLY BETWEEN THE MEMBERS, THE OPPOSITE ENDS OF EACH OF SAID TRANSFER RINGS CARRYING OPPOSITELY FACING CLUTCH TEETH OF COMPLEMENTARY SHAPE TO THOSE CARRIED BY SAID MEMBERS AND BY EACH OF THE OTHER TRANSFER RINGS, SAID CLUTCH TEETH BEING SHAPED TO DEFINE WHEN ENGAGED A PLURALITY OF CIRCUMFERENTIALLY SPACED GENERALLY RECTANGULAR RECESSES THEREBETWEEN, AND FORCE TRANSFER ELEMENTS REMOVABLY DISPOSED IN SAID RECESSES, THE VERTICAL DIMENSION OF SAID ELEMENTS BEING SOMEWHAT GREATER THAN THAT OF THE CLUTCH TEETH WHEREBY TO MAINTAIN ADJACENT TRANSFER RINGS IN SPACED APART RELATION, SAID ELEMENTS BEING CONSTRUCTED OF FLEXIBLE RESILIENT NON-METALLIC MATERIAL. 